Mastitis takes toll on dairy reproduction

Battling mastitis has always been an ongoing, difficult challenge for the dairy producer.

Research has shown that, in addition to the $200 economic loss per diagnosed case of mastitis from the three "P's" (premiums, production, pails of milk), mastitis can take a toll on a fourth "P" - pregnancy.

Reproductive performance is quickly becoming the biggest challenge in dairy herds' profitability. Based on the 2007 National Animal Health Monitoring System Survey, reproductive inefficiency is second when it comes to involuntary culling.

How does mastitis affect reproduction and ultimately pregnancy?

Elevated body temperatures possibly resulting from both gram-negative and gram-positive infections may decrease feed intake, leading to a more pronounced negative energy balance and delayed ovulation. Endotoxins from mastitis bacteria can cause increased blood cortisol levels. Cortisol is a hormone that blocks the release of luteinizing and follicle stimulating hormone secretions, both of which disrupt the reproductive cycle.

Finally, cytokine production increases during a mastitis event leading to premature luteolysis resulting in embryonic death or abortion.

Several studies show support of the detrimental effects of mastitis on reproduction, including extended interval to first breeding, post-calving, reduced pregnancy per breeding, reduced embryonic and fetal survival, and increased incidence or abortions.

A University of Tennessee study found cows with subclinical infections that eventually became clinical cases during the breeding period were most affected. It took these cows 93.9 days until their first service as compared to 67.8 days in cows without mastitis.

Services per conception increased from 1.6 services to 4.3 services per conception if a cow had mastitis prior to first artificial insemination post-calving. With a 26-day delayed first service and multiple services, subsequently, days open increased from 85.4 days in cows with no mastitis to 196 days open in cows with mastitis.

Regarding abortions, a UC-Davis study showed cows developing mastitis during any period of their lactation showed an increase in abortions between 42 and 180 days of service. The abortion rate was found to be 11.0 percent for cows having mastitis at any time during their lactation while cows not having mastitis had almost one-half as many abortions with a 5.8 percent abortion rate.

A 2004 study demonstrated a cow diagnosed pregnant at 30 to 45 days after artificial insemination and having mastitis before first pregnancy diagnosis were still at higher risk of pregnancy loss than those cows not having mastitis. From this and other studies, mastitis during early pregnancy may not only cause immediate embryonic death, but also effects to fetal development which led to increased abortion rate.

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Mastitis takes toll on dairy reproduction

Battling mastitis has always been an ongoing, difficult challenge for the dairy producer.

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